不同构造背景天然气储层成岩作用及孔隙演化特点

克拉通盆地气藏储层经历地史时间长,构造运动旋回多,导致成岩环境多变,成岩作用复杂且长期叠加,孔隙演化也经历几个来回,储层现今孔隙度小。根据所处构造部位、圈闭类型和储层性质,气藏又细分为古隆起构造气藏、背斜气藏和岩性气藏3种类型。这些气藏储层的成岩序列及孔隙演化有所不同。前陆盆地冲断带和斜坡带气藏储层经历地史时间较短,构造运动旋回较少,埋藏速率较大,成岩序列及孔隙演化较为简单,储层现今孔隙度较小。裂谷盆地气藏储层地史时间短暂,构造运动旋回少,埋藏速率大,成岩序列和孔隙演化史简单,储层现今孔隙度较大。

Characteristics of diagenesis and pore evolution of gas reservoirs formed in different tectonic settings

Gas reservoirs in craton basins have experienced multicyclic tectonic movement during the long geologic history, resulting in varied diagenetic environments, complex diagenesis and long-term superimposition. Their pores have experienced several cycles of evolution and the present porosities of reservoirs are low. According to the structural location, trap type and reservoir nature, the gas reservoirs can be further subdivided into three types, including palaeohigh structural gas reservoirs, anticlinal gas reservoirs, and lithologic gas reservoirs. Their diagenetic sequences and pore evolutions are somewhat different. Gas reservoirs in the thrust belt and slope zone of foreland basin are characterized by their relatively short geologic histories, relatively less tectonic cycles, relatively rapid burial and relatively simple diagenetic sequence and pore evolution, so the present porosities are relatively small. While gas reservoirs in rift basin are characterized by their short geologic histories, less tectonic cycles, rapid burial and simple diagenetic sequence and pore evolution, so the reservoirs have relatively large porosities.